In 1972, five burglars were caught breaking into the Democratic National Committee Headquarters at the Watergate Hotel and office complex in Washington, D.C. Media and government investigation of the break-in revealed that the burglars were associated with the campaign to re-elect Nixon. The inquiries also revealed that the president and his aides had probably abused their power in other ways as well.
"During the congressional hearings on the break-in scandal, it was revealed that President Nixon had installed a tape-recording device in the Oval Office. The special prosecutor in charge of the case wanted to get tapes of the Oval Office discussions to help prove that President Nixon and his aides had abused their power and broken the law."
Nixon's Views on Presidential Power: Excerpts from a 1977 Interview with David Frost